Cable operators and vendors, such as Big Band, Motorola, Cisco, and Imagine Communications, have developed and are further refining systems to measure bit/bandwidth demand or “pull” by cable consumers and allocate capacity within a cable plant node on a real-time dynamic basis. These types of systems are referred to as “switched digital video” systems. Switched digital video (“SDV”) systems are being implemented to resolve growing consumer demand of cable bit/bandwidth. With hundreds of possible television channels and an increasing number of high-definition (“HD”) channels, cable service providers are being stretched to the limits of their network capacity in order to provide uninterrupted, quality service to their subscribers. In addition to audio and video data transmitted for television services, many providers also package Internet, Video-on-demand and digital telephone services to subscribers—all within the same cable infrastructure.
To accommodate the increased demand for bits/bandwidth, cable providers limit the transmission of a particular channel until it is requested by a subscriber. For example, a certain channel is not constantly broadcast out a home, or neighborhood. When a subscriber tunes to that channel on the digital set-top box, a signal is sent to the cable provider to “turn-on” the channel. The provider then transmits the stream of data containing that channel's video and audio through the cable to the set-top box and on to the subscriber's television. Should a second subscriber in the same service area call up that same channel, the stream is forwarded on to that set top box eliminating the need for a second stream of the same channel.
The transmission speeds of signals over the cable lines is fast enough that the subscriber is unaware that seconds before tuning to that station, the station was not being broadcast at all.
Hybrid SDV systems provide for the more popular channels such as broadcast networks and popular networks (e.g. ESPN, CNN, etc.) to be constantly broadcast to a home, while less popular channels would be handled in much the same way as a video-on-demand (VOD) session except that instead of having the characteristics of a unicast (only one-to-one) transmission, it would have the characteristics of a multicast transmission (2nd, 3rd, etc. viewers of a program channel would be joined to the stream initiated into the node by the 1st viewer). Thus, more popular channels would always be available while channels which are switched would only be available (similarly to VOD) when bandwidth is available.
Further, as the cable plant is transmitting both the Moving Picture Experts Group (MPEG) data (for typical video programming) and Internet Protocol (IP) data, some vendors and cable operators are designing for bandwidth to also be dynamically allocated on a shared basis between IP uses and MPEG uses.
Current switched digital video systems are designed to alleviate and overcome bandwidth transmission limitations from the consumer on a “pull” basis (i.e., dynamically allocating bandwidth based upon subscriber usage and demand). There remains an untapped resource for advertisers and cable providers alike in adapting a dynamic bandwidth allocation protocol on a “push” basis to opportunistically exploit the gaps or holes in the available bandwidth. That is, dynamically allocating'additional, unused bandwidth to certain channels for the inclusion of additional services, such as advanced advertising and content delivery